Fan enabling increased air volume

ABSTRACT

A fan enabling increased air volume includes at least a fan wheel and a driving unit for driving the fan wheel to maintain a uniform rotating speed. The fan wheel includes a hub and a plurality of blades radially extended from an outer periphery of the hub. The blades may be arranged on the hub in different manners, such as having a preceding blade overlapped a following blade, or having a blade root installation angle smaller than 53° and a blade tip inclination angle smaller than 46°, or having a solidity of blade roots larger than 1.5 and a solidity of blade tips larger than 1, so that the fan wheel produces increased air volume and accordingly enhanced cooling power at the uniform rotating speed.

This application is a Divisional of co-pending application Ser. No.10/863,337, filed on Jun. 9, 2004, and for which priority is claimedunder 35 U.S.C. § 120, the entire contents of all are herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a fan enabling increased air volume,and more particularly to a fan with enhanced cooling power.

BACKGROUND OF THE INVENTION

With the increasing developments in technological fields, various kindsof electronic products are designed to provide more functions so as toincrease their value in use. The increased functions necessitate theprovision of more components or parts in a system having a fixed volume.The large quantity of components or parts in the electronic productresult in reduced internal spaces of the system while produce more heatin the limited internal spaces of the system to necessitate the use ofcooling means to carry away the produced high amount of heat. A coolingfan is most frequently selected to solve the problem of heat produced inthe system because it produces convective airflows to carry away theproduced heat from the system. However, when the airflows produced bythe cooling fan inward flow through the system, they are inevitablyimpeded by the components or parts densely arranged in the system toresult in largely reduced cooling effect. Therefore, it is necessary toincrease the air volume and air pressure produced by the cooling fan tomaintain the expected cooling effect. Currently, there are two ways toachieve this purpose. The first way is to increase the rotating speed ofthe motor of the fan, and the second way is to change the bladestructure of the fan. However, the increased motor rotating speed wouldresult in consumption of more power and accordingly waste of moreenergy.

FIG. 1 is a graph showing different fan characteristic curves for ageneral fan used with a system having a relatively small number ofcomponents or parts arranged therein. When the fan is started tooperate, airflows produced by the fan are interfered in their flow pathsby the components in the system. That is, the impedance of the internalcomponents of the system will prevent the airflows produced by the fanfrom flowing smoothly to result in loss of air pressure. In the graph ofFIG. 1, the curve A1 is a system impedance curve representing changes inthe loss of air volume produced by the fan, and will become lowered whenthe number of components or parts in the system is low; the curve T isan air volume curve representing the operating characteristic of the fanmeasured in an air tunnel; the point P is an intersection of the curveA1 with the curve T representing an operating point of the system; andthe circled area A surrounding the point P is an operating rangerepresenting the operating performance of the fan used with the systemhaving lower number of internal components.

Please refer to FIG. 2 that is a graph showing different fancharacteristic curves for a fan having overlapped blades and operatingat non-uniform rotating speeds for effectively solving the problem ofproduced heat in a system having highly densely arranged internalcomponents or parts. When the overlapped blades of the fan are rotatedto produce airflows, the airflows are interfered in their flow paths bythe components in the system. That is, the impedance of the internalcomponents of the system will prevent the airflows produced by theoverlapped blades of the fan from flowing smoothly to result in loss ofair pressure. In the graph of FIG. 2, the curve B1 is a system impedancecurve representing changes in the loss of air volume produced by thefan, and will become higher when the number of components or parts inthe system is high; the curve T1 is an air volume curve representing theoperating characteristic of the fan with overlapped blades measured inan air tunnel; the point P1 is an intersection of the curve B1 with thecurve T1 representing an operating point of the system; and the circledarea Q surrounding the point P1 is an operating range representing theoperating performance of the fan with overlapped blades operated atnon-uniform rotating speeds to carry away the heat produced in thesystem.

In the graph shown in FIG. 3, the curve T3 represents an air volumecurve for a fan having a motor with increased number of coils in anattempt to upgrade the fan performance; and point P2 is an intersectionof the curve T3 with the system impedance curve B1 representing anoperating point of the system. The operating point P2 is obviously muchhigher than the operating point P1 at the intersection of the curve T1with the system impedance curve B1. That is, the whole curve T3 ishigher than the curve T1 and represents the fan with motor havingincreased number of coils provides increased air volume. However, themotor with increased number of coil would largely increase the powerconsumption thereof and tends to overheat and burn out due to increasedrotating speed.

It is therefore tried by the inventor to develop a fan enablingincreased air volume that increases air pressure and volume without theneed of increasing the power for drive the fan.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a fan wheelhaving a plurality of blades that may be differently arranged on a hub,so that the blades either overlap one another, or have a blade rootinstallation angle smaller than 53° and a blade tip inclination anglesmaller than 46°, or have a solidity of blade roots larger than 1.5 anda solidity of blade tips larger than 1, so that the fan wheel is able toproduce increased air volume and enhanced cooling efficiency at auniform rotating speed.

Another object of the present invention is to provide a fan wheel thatoperates at a uniform rotating speed to save power consumption needed todrive the fan wheel.

To achieve the above and other objects, the fan enabling increased airvolume according to the present invention includes at least a fan wheeland a driving unit for driving the fan wheel to maintain a uniformrotating speed. The fan wheel includes a hub and a plurality of bladesradially extended from an outer periphery of the hub.

In a first embodiment of the present invention, the blades are arrangedon the hub with a preceding blade overlapping a following blade. In asecond embodiment of the present invention, the blades are arranged onthe hub with a blade root installation angle smaller than 53° and ablade tip inclination angle smaller than 46°. In a third embodiment ofthe present invention, the blades are arranged on the hub with asolidity of blade roots larger than 1.5 and a solidity of blade tipslarger than 1. In either case, the fan wheel is able to produceincreased air volume and accordingly enhanced cooling power at theuniform rotating speed.

Further scope of the applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thefollowing detailed description and the accompanying drawings, which aregiven by way of illustration only, and thus are not limitative of thepresent invention, and wherein:

FIG. 1 is a graph showing fan characteristic curves for a conventionalfan used with a system having a relatively small number of components orparts arranged therein;

FIG. 2 is a graph showing fan characteristic curves for a conventionalfan with overlapped blades and used with a system having a relativelylarge number of components or parts arranged therein;

FIG. 3 is a graph comparing a fan characteristic curve for aconventional fan having a motor with increased number of coils with thefan characteristic curves shown in FIG. 2;

FIG. 4 is an exploded sectional view of a fan according to a firstpreferred embodiment of the present invention;

FIG. 5 is an assembled sectional view of FIG. 4;

FIG. 6 is a top plan view of the fan according to the first preferredembodiment of the present invention;

FIG. 7 is a graph showing a rotating speed deviation curve for a fanhaving a uniform rotating speed according to the first preferredembodiment of the present invention;

FIG. 8 is a graph comparing an air volume curve for the uniform-speedfan according to the first preferred embodiment of the present inventionto fan characteristic curves for a conventional fan having non-uniformrotating speeds and used with a system having densely arranged internalcomponents;

FIG. 9 is a top plan view of another fan according to the firstpreferred embodiment of the present invention with blades thereofoverlapped in a second manner;

FIG. 10 is a top plan view of a further fan according to the firstpreferred embodiment of the present invention with blades thereofoverlapped in a third manner;

FIG. 11 is a stretch-out sectional view showing blade roots for a fanaccording to a second preferred embodiment of the present invention;

FIG. 12 is a stretch-out view showing blade tips for the fan accordingto the second preferred embodiment of the present invention;

FIG. 13 shows a stretch-out view of a hub and sectioned side view ofblade roots for a fan according to a third preferred embodiment of thepresent invention;

FIG. 14 shows the solidity of blade roots for the fan according to thethird preferred embodiment of the present invention;

FIG. 15 shows a stretch-out view of a hub and sectioned side view ofblade tips for the fan according to the third preferred embodiment ofthe present invention; and

FIG. 16 shows the solidity of blade tips for the fan according to thethird preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 4, 5, and 6, in which a fan enabling increased airvolume according to a first preferred embodiment of the presentinvention is shown. As shown, the fan of the present invention includesat least a housing 21, a fan wheel 22, and a driving unit 23. The fanwheel 22 includes a hub 221 and a plurality of overlapped blades 222that radially outward extend from an outer periphery of the hub 221.Each of the blades 222 includes a blade root 2221 directly connectedwith the hub 221, a blade body 2222 extended from the blade root 2221and having a first blade edge 2223 and a second blade edge 2224, and ablade tip 2225 located at an outer end of the blade body 2222. Theblades 222 overlap one another in such a manner that the blade root 2221and an area including an upper part of the blade body 2222 and the firstblade edge 2223 of a preceding blade 222 overlaps the blade root 2221and an area including a lower part of the blade body 2222 and the secondblade edge 2224 of a following blade 222. The hub 221 includes a spindle2211 having a neck portion 22111 formed thereon for a retaining ring 26to engage therewith. The housing 21 includes a hub seat 211 with ahollow bushing 212 provided thereon for a bearing 25 to mount therein.The driving unit 23 includes a driving circuit board 231, a stator 232,and a rotor 233.

To assemble the fan of the present invention, first firmly fix the rotor233 in the hub 221 of the fan wheel 22, and then sequentially positionthe retaining ring 26 and the bearing 25 in the bushing 212, and thenput the driving circuit board 231 and the stator 232 around the bushing212. Thereafter, extend the spindle 2211 of the fan wheel 22 through thebearing 25 with the retaining ring 26 engaged with the neck portion22111 of the spindle 2211, so that the spindle 2211 is rotatablyconnected to the bushing 212 without the risk of separating from thebushing 212. Finally, connect the driving circuit board 231 to thestator 232, which is magnetically connected to the rotor 233, so thatthe stator 232 and the rotor 233 are excited when the driving circuitboard 231 produces currents. In this manner, the fan wheel 22 couldrotate at a uniform speed as soon as it is started, and producesairflows.

Please refer to FIGS. 4 and 7 at the same time. The fan with overlappedblades and operated at a uniform rotating speed, as described withreference to FIGS. 4, 5, and 6, has a rotating speed deviation curve F1for a rotating speed preset for the fan. When the curve F1, under thepreset fixed rotating speed, indicates a deviation within a range of±8%, the air volume produced by the fan increases gradually. That is,when the fan with overlapped blades has a uniform rotating speed and arotating speed deviation of the fan between a starting speed and an endspeed is limited to a range of ±8%, the air volume produced by the fanincreases. And, when the rotating speed deviation between the startingspeed and the end speed is limited to 0%, the fan with overlapped bladeshaving a uniform rotating speed actually has a fixed rotating speed,which allows the fan to produce further increased air volume. The fan ofFIG. 4 has an air volume curve T2 as shown in FIG. 8. That is, the curveT2 is obtained when the fan with overlapped blades 222 according to thefirst preferred embodiment of the present invention rotates at a uniformspeed. The curve T2 intersects with the system impedance curve B1 at apoint that is a system operating point P2. As can be seen from FIG. 8,the operating point P2 of the fan with overlapped blades and uniformrotating speed has a position in the operating area Q the same as theposition of the operating point P2 at the intersection of the air volumecurve T3 of the fan with motor having increased number of coil with thesystem impedance curve B1, and is obviously higher than the operatingpoint P1 of the general fan with overlapped blades and non-uniformrotating speed. That is, the air pressure and air volume correspondingto the operating point P2 are obviously higher than that correspondingto the operating point P1. In other words, the whole air volume curve T2indicates the fan of the present invention having overlapped blades anduniform rotating speed has an optimal operating performance to providelargely increased air pressure and effective cooling of a system withdensely arranged internal components or parts. The fan of the presentinvention eliminates the drawbacks existed in the conventional fan withmotor having increased number of coils, such as increased powerconsumption and easy burnout of motor due to high rotating speedthereof, while upgrades the fan performance to produce increased airpressure and air volume without increasing the power needed by themotor.

FIGS. 9 and 10 shows two fans according to the first preferredembodiment of the present invention but have a plurality of blades 222overlapped one another in different manners. In FIG. 9, the blades 222overlaps one another in such a manner that the blade root 2221 of apreceding blade 222 overlaps the blade root 2221 of the following blade222. In FIG. 10, the blades 222 overlaps one another in such a mannerthat the blade body 2222 of a preceding blade 222 overlaps the bladebody 2222 of the following blade 222. In either case, the fan of thepresent invention provides an optimal performance to produce increasedair pressure and enhanced cooling efficiency without increasing thepower consumption thereof.

Please refer to FIGS. 11 and 12 that are spread-out views of a fan wheel32 for a fan according to a second preferred embodiment of the presentinvention to show a sectioned side view of blade roots 3221 and a sideview of blade tips 3225, respectively, of the blades 322 on the fanwheel 32. The fan wheel 32 is structurally and functionally similar tothe fan wheel 22 in the first preferred embodiment, except that theblades 322 on the fan wheel 32 do not overlap one another, and the bladeroot 3221 connected with the hub 321 has an inclination equal to anangle contained between a blade chord C3 at the blade root 3221 and ahorizontal line. That is, the blade root 3221 has an installation angleθ1 smaller than 53°. Moreover, the blade tip 3225 of the blade 322 onthe hub 321 has an inclination equal to an angle contained between ablade chord C4 at the blade tip 3225 and a horizontal line. That is, theblade tip 3225 has an inclination angle θ2 smaller than 46°. With thesearrangements, the fan according to the second preferred embodiment ofthe present invention rotating at a uniform speed can produce increasedair pressure and air volume to achieve an optimal performance andincreased cooling efficiency without increasing the power consumptionthereof.

FIGS. 13 to 16 are spread-out views of a fan wheel 42 for a fanaccording to a third preferred embodiment of the present invention,wherein FIGS. 13 and 14 are sectioned side views of blade roots 4221,and FIGS. 15 and 16 are side views of blade tips 4225 of the blades 422on the fan wheel 42. The fan wheel 42 is structurally and functionallysimilar to the fan wheel 22 in the first preferred embodiment, exceptthat the blades 422 on the fan wheel 42 do not overlap one another, anda solidity of blade roots of the blades 422 connected to the hub 421 islarger than 1.5. That is, C1÷S1>1.5, where C1 is referred to as a bladechord at the blade root and represents a linear distance from an upperend 42211 a to a lower end 42212 a of a blade root 4221 a of a blade 422a, and S1 is a linear distance from the upper end 42211 a of the bladeroot 4221 a of a blade 422 a to the upper end 42211 b of the blade root4221 b of an adjacent blade 422 b, or a linear distance from the lowerend 42212 a of the blade root 4221 a of a blade 422 a to the lower end42212 b of the blade root 4221 b of an adjacent blade 422 b (see FIGS.13 and 14). Moreover, a solidity of blade tips of the blades 422 islarger than 1. That is, C2÷S2>1, where C2 is referred to as a bladechord at the blade tip and represents a linear distance from an upperend 42251 a to a lower end 42252 a of a blade tip 4225 a of a blade 422a, and S1 is a linear distance from the upper end 42251 a of the bladetip 4225 a of a blade 422 a to the upper end 42251 b of the blade tip4225 b of an adjacent blade 422 b, or a linear distance from the lowerend 42252 a of the blade tip 4225 a of a blade 422 a to the lower end42252 b of the blade tip 4225 b of an adjacent blade 422 b (see FIGS. 15and 16). With the above arrangements, including the non-overlappedblades, a solidity of blade roots larger than 1.5 and a solidity ofblade tips larger than 1, and a uniform rotating speed, the fanaccording to the third preferred embodiment of the present invention canproduce increased air pressure and air volume to achieve an optimalperformance and increased cooling efficiency without increasing thepower consumption thereof.

The invention being thus described, it it will be obvious that the samemay be varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A fan enabling increased air volume, comprising: a fan wheel, and adriving unit for driving said fan wheel to maintain a uniform rotatingspeed; wherein said fan wheel includes: a hub, and a plurality of bladesradially extended from an outer periphery of said hub; wherein a root ofeach of said a plurality of blades has an installation angle smallerthan 53°, and a tip of each of said a plurality of blades has aninclination angle smaller than 46°, whereby said fan wheel producesincreased air volume and enhances cooling power at said uniform rotatingspeed.
 2. The fan enabling increased air volume as claimed in claim 1,wherein said driving unit includes a driving circuit board.
 3. The fanenabling increased air volume as claimed in claim 1, further comprisinga housing in which said fan wheel and said driving unit are mounted. 4.The fan enabling increased air volume as claimed in claim 1, whereinsaid uniform rotating speed of said fan wheel has a deviation within arange of ±8%.